The biggest guff spouted on the subject is that raising the limit will increase emissions by 20%. No, it’s not mph that matters – it’s rpm. At 70mph, old petrol cars rev at 3,500rpm. Longer-geared diesel or newer cars rev at 2000, using about a third less fuel and producing a third less CO2. On safety, what about middle-lane blockers who not only waste motorway space but cause bunching and get away scot-free when “accidents” occur? But the whole “debate” – about driving by numbers instead of context – is puerile.